WeIrD Guage Light Problem
 

Here is a weird one for you guys...

I installed a boost guage in my center console vent hole... i used the power and ground that i found on the harness that goes to the hazard/light flip up button combo. it works, but the weird thing is when i adjust all of the guage lights down.. the light on the boost guage gets brighter, and vise versa.... and some times it works, and some times it does not... Any ideas?

maybe you have the ground/hot flipped? just a thought..may be completely wrong though

search on miata.net (I know, I know) there its been discussed before and the solution as well. Its something to do with the way the dimmer switch works and how you can get around that.

you can hook it up in place of the light that's in the cup holders. thats what i did.

Lol, wtf i dont have cupholders. No fair!

Yeah, i guess thats what i will do, couldnt find anything on m.net.. i dont see why the wires i used didnt work thought.. the lights inside the buttons between the vents dim with the rest of the dash lights.. i thought that was what i tapped into

I have a set of Autometer gauges and they are very dim as it is so I just connected it to the power and ground wires on the radio.

my gauges where the same way.i switch the power(gauge) wire to the other power(dimmer switch),i cant adjust the brightness.

no cup holder light here either.

You dim a gauge bulb by decreasing supplied voltage with a potentiometer--meaning you increase or decrease resistance on the +12V side of the circuit to make the dimmer or brighter.

Unfortunately, the miata dimmer circuit works by breaking the ground with an oscillator. Instead of lowering supplied votage, it switches the circuit on & off rapidly. The switching speed (duty cycle) is determined by the dimmer knob.

What brand gauge do you have? How is it backlit--incadecent or led?
Most likely you have to do one of the two things:
* Hook backlight up to a source that receives +12V with parking lights. This will illuminate the backlight, but will not have dimmer control
* Do the same as above, but add a potentiometer in the dash or center console. Gauge will dim independantly of the dash

thanx ben, i get it now.. I figured it was something gay that mazda did just to piss me off. The guage is a VDO and it is incandesent

he means the light in the ashtray

I vampired right onto the dimmer switch wires....my boost gauge dims perfectly...as long as you only use a light buld with ground and + you should be able to get it to work...

maybe i need to tap right into that.. the weird thing is, it dims and brightens fine, but its reversed from the other lights... i dont understand how that can happen

reverse the polarity and see what happens.

yah, dimmer wires don't provide 0v for dim and 12v for bright. If I recall, it will provide 12V when fully dimmed. At full bright it provides GND or 0V. so you want the + wire going to 12V and the -/gnd wire going to the dimmer control wire.

Matt

Yeah, the "dimmer" knob is in the ground path. At full bright, it just leaves the contact to ground at 100% dc.